A high-ranking Chinese delegation led by Communist Party Politburo member Li Changchun is set to leave for North Korea in an effort to restart talks on Pyongyang's nuclear weapons programs.

The Chinese delegation's visit to Pyongyang comes just after South Korea revealed that its scientists had conducted clandestine nuclear experiments in 1982 and 2000.

The revelations put multiparty talks on North Korea's nuclear program on uncertain ground, with North Korean officials saying the experiments could trigger a nuclear arms race between the two Koreas.

North Korea's remarks were not welcomed by China, which is hoping to broker a fourth round of negotiations to end Pyongyang's nuclear weapons programs.

At a briefing on Thursday, Chinese Foreign Ministry spokesman Kong Quan said China hopes the six-party talks will stay on track.

"We hope that the relevant parties can display patience and restraint, and pragmatism at this moment in the joint push for the six-party talks to be held by the end of September," he said.

In the last set of negotiations in June, all sides agreed to meet by the end of this month. However, no date has been announced for the discussions, which also include Japan, Russia, and the United States.

North Korea has called the negotiations useless, and said talks could not continue as long as the United States maintains what Pyongyang calls a hostile policy toward the North.

China's latest delegation, which leaves for Pyongyang on Friday, hopes to convince the North Koreans to return to the negotiating table.

Beijing - North Korea's main supplier of food and fuel - has in the past offered economic incentives to the deeply impoverished Communist nation in exchange for Pyongyang's participation in negotiations.

As the Chinese delegation prepared to leave for North Korea, Chinese officials did not say what - if any - incentives they might be prepared to offer North Korea this time.